This invention relates to pipes made from polymeric material, and more particularly to pipes made as segments which are assembled into larger pipe systems during installation.
During recent years, it has become more and more common for pipes for the transmission of fluids to be made from plastic materials.
Non-metal materials are made into various types of pipes by several methods. For instance, it is known to extrude PVC into various shaped pipes. Another more economical method is the corrugated pipe technique, which uses blow mold and vacuum mold techniques to produce a pipe which is formed as extruded tubes of a polymer such as HDPE (high density polyethylene). Systems for fabricating such corrugated pipes are sold by Corma, Inc. of Concord, Ontario. A system of this type is also described in U.S. Pat. No. 5,296,188, which is herein incorporated by reference.
Polymer material pipes are generally manufactured as continuous extrusions which are then cut into sections. Frequently, each section has a male end and a female end, and these sections are linked sequentially across the distance needed for the pipe to extend. The female end of the pipe, sometimes called a bell, receives the male end, sometimes called a spigot, of the next pipe therein.
One problem presented in such pipes derives from the fact that, during fabrication, the material from which the pipe is made is heated, and then cooled. As different portions of the pipe cool and shrink at different rates, stresses are created. If the pipe is then exposed to heat, even such as that of strong sunlight, it may cause enough warming to soften portions of the pipe.
The result of this is that portions of the bell are altered from the desired shape. As a result, the bell, which is optimally an open flared cone or skirt with a circular mouth, xe2x80x9cflowersxe2x80x9d, i.e., deforms into a roughly clover-leaf or flower cross-section. This flowered structure presents problems when the pipe sections are to be assembled, since the puckering of this shape may make the female end of the pipe too small to easily accommodate the male end of the next pipe section. This means that the construction crew must try to pry the flowered bell apart to insert the male portion. This is inefficient in terms of labor costs and time. Moreover, the flowering can render the pipe section completely unusable.
Similarly, stacking of the pipe section can create loads in the female end of the pipe section. If environmental factors such as heat created by sunlight or high ambient temperatures are present, this can soften the material to the degree that deformation occurs.
It is therefore an object of the invention to provide a pipe section having a female end with a strengthened periphery.
It is also an object of the invention to provide a pipe section with a female end resistant to deformation.
It is another object of the invention to provide a pipe section which is readily connected with another pipe section to form a pipe assembly.
It is still another object of the invention to provide a pipe assembly which is efficiently and cost-effectively fabricated in the field and is reliably sealed against leakage.
It is a further object of the invention to provide a method and apparatus for making the pipe section of the invention.
It is yet another object of the invention to provide a method of fabricating the pipe assembly of the invention.
Accordingly, in one aspect the invention is a pipe section which comprises a segment of polymeric material configured as a conduit having an end strengthened by a reinforcing structure formed integrally of said material around the periphery of said end.
In another aspect, the invention is a pipe assembly for accommodating fluid flow therethrough, which includes a first pipe section comprising a segment of polymeric material configured as a conduit and having a male end and a female end, said first pipe section""s female end being flared and being strengthened by a reinforcing structure formed integrally of said material around the periphery of said female end, and a second pipe section comprising a segment of polymeric material configured as a conduit and having a male end and a female end, said male end of said second pipe section being in the female end of the first pipe section such that fluid may flow from one of said sections into the other.
In a further aspect, the invention is a method of forming a pipe section, which comprises subjecting an end of a segment of polymeric material configured as a conduit to conditions sufficient to render the material proximate such end plastic, and turning the plastic polymeric material at such end back away from the end to form an integral reinforcing structure.
In yet another aspect, the invention is method of fabricating a pipe assembly for accommodating fluid flow therethrough, said assembly including a first pipe section comprising a segment of polymeric material configured as a conduit and having a male end and a female end, said female end being flared and being strengthened by a reinforcing structure formed integrally of said material around the periphery of said female end, and a second pipe section comprising a segment of polymeric material configured as a conduit and having a male end and a female end, which method comprises bringing the female end of said first pipe section and the male end of said second pipe section into approximate registration by inserting the male end of the second pipe into the flared female end of the first pipe section, and connecting the male end of the second pipe section and the female end of the first pipe section when the two sections are in alignment, such that fluid may flow from one of said sections into the other.
In still another aspect, the invention is an apparatus for forming a reinforcing structure on an open end of a polymeric pipe section, which has a mandrel having a wall for contacting said pipe section. The mandrel includes a first portion wherein the wall is configured to be received in the open end of the pipe section, and another portion in which the wall extends outwardly of the first portion in arcuate fashion such that an annular pocket is formed. The apparatus has means for holding the pipe section in an orientation such that it and the mandrel can be brought into contact, with the mandrel""s first portion being first received in the opening at the end of the pipe section. The apparatus also has means for causing movement of the mandrel and the pipe section holding means relative to one another such that the mandrel and the pipe section come together with the mandrel""s first portion being received by the opening at the end of the pipe section, and thereafter the annular pocket of the third portion coming into contact with and deforming the end of the pipe section to form a reinforcing structure.
Of course, it will be understood that the invention pertains not only to straight-line pipe sections but also to all other configurations, such as elbow-shaped or T-shaped fittings.
Substantial benefits are conferred by practice of the invention. The provision of a reinforcing structure integral with the subject pipe section, proximate the periphery of the female end, effectively strengthens the structure so that it maintains its desired shape, resists deformation during storage before use, and can withstand rough handling during connection of other piping to it. The pipe assembly incorporating such pipe section is cost effectively fabricated in the field and has increased strength at the point of interface during the connection operation, with the result that such operation is made easier and more efficient. And, the method and apparatus for making the pipe section, as well as the method for making the aforementioned pipe assembly, of the invention are correspondingly convenient and cost effective.
Other objects and benefits of the invention will become apparent from the present specification, and the invention will be set forth in the claims.